The present invention relates to molded plastic siding panels for covering exterior walls on buildings.
Molded plastic siding panels for exterior building walls are known in the prior art. These molded panels are made from synthetic thermoplastic polymers, including polypropylene, polyethylene, and various mixtures and copolymers thereof.
Laterally elongated molded plastic panels are nailed to a wall support surface in horizontal rows partially overlapping each other in order to provide a pleasing appearance combined with a water-resistant protective layer over the support surface.
The molded plastic panels are typically installed by nailing several adjacent courses to a wall support surface, starting with a bottom course. A lower marginal edge region of each panel in courses above the bottom course overlaps a panel in the course immediately below. Side marginal edge regions of each panel overlap side marginal regions of adjacent panels.
Various mechanisms have been proposed for interlocking lower marginal edge regions of the plastic panels with panels in the course immediately below. One disadvantage of prior art interlocking mechanisms is that when one panel is damaged and must be replaced, at least one other panel must also be removed. Accordingly, there still remains a need for a means for interlocking adjacent upper and lower regions of plastic panels that allows for removal and replacement of only a single panel without affecting the other panels.
Overlapping side marginal edge regions of adjacent plastic panels has also posed problems in the prior art. Because the panels are relatively long, locking the panels together in their side marginal edge regions may cause bowing after installation when the panels undergo thermal expansion. Thermal expansion contraction accompanying temperature changes may also fracture overlapped portions of the panels unless suitable accommodations are provided for panel movement.
The panels commonly include a plurality of rows of simulated wood shingles in which individual shingle elements are spaced apart by gaps of identical width. Because all panels are produced by a single mold, they have an identical appearance from panel to panel. This identical width of all gaps and the identical appearance from panel to panel have heretofore made more readily noticeable the spacings between elements of laterally adjacent panels accompanying temperature variations. Accordingly, there still remains a need for molded plastic panels that will camouflage any spacings accompanying thermal contraction and expansion.
A principal objective of the present invention is to provide a molded plastic panel having an interlock mechanism locking the panel firmly in place, yet still permitting replacement of the panel if it becomes damaged without removing or damaging adjacent panels.
A related objective of the invention is to provide a molded plastic panel having side marginal edge regions for interlocking laterally adjacent plastic panels without bowing or fracturing the panel during installation or upon thermal expansion and contraction.
A further objective of the invention is to camouflage spacings of varying width between adjacent panels resulting from thermal expansion and contraction.
Another objective of the invention is to provide a process for making a molded plastic panel including an attachment hem having at least one locking tab, without any through openings in the attachment hem behind the locking tab.
Additional objectives and advantages of the invention will become apparent to persons skilled in the art from the following detailed description.
In accordance with the present invention, there is provided a thermoplastic panel for covering exterior walls on buildings. The panel is made from a thermoplastic polymer selected from the group consisting of polyolefins, polycarbonate, polyvinyl chloride, and mixtures and copolymers thereof. Polyolefins, especially polypropylene in mixtures and copolymers with polyethylene, are particularly preferred. The thermoplastic panel is preferably manufactured by injection molding.
The thermoplastic panel includes a body, an attachment hem or nailing hem adjacent an upper portion of the body, a locking tab attached to the attachment hem, and a folding flange attached to a lower portion of the body.
The attachment hem is preferably adjacent an upper portion of the body. The attachment hem defines a plurality of spaced, laterally elongated attachment slots or nailing slots for attaching the panel to an exterior building wall.
A locking tab attached to the hem includes a downwardly extending lower leg portion and a forwardly extending upper leg portion connecting the hem with the lower leg portion. The lower leg portion defines an arcuate socket facing rearwardly of the panel. In a preferred embodiment, a plurality of outwardly extending ribs connect the locking tab with a front surface portion of the attachment hem.
A folding flange attached to a lower portion of the body includes a forwardly facing locking lip for engaging a socket in the locking tab on an adjacent panel and a hinge connecting the locking lip with the body. The hinge is formed integrally with the lip and the body and has lesser thickness than the lip or the body.
The hinge preferably has less than half the thickness of the body or the locking lip. In a particularly preferred panel wherein a portion of the body supporting the hinge has a thickness of about 0.070 inch, the hinge has a thickness of about 0.010-0.020 inch. The preferred embodiment also includes a hinge support web extending rearwardly of a front surface portion of the body. The hinge support web supports the hinge and the hinge supports the locking lip. The hinge extends about {fraction (1/16)} inch (0.063 in.) between the hinge support web and the locking lip.
The panel body includes at least one laterally extending row of simulated shingles. The shingles each have a bottom wall extending between two side walls, and a front surface portion including a bottom end portion adjacent the bottom wall and a top end portion spaced upwardly from the bottom wall.
A particularly preferred panel body includes an upper row and a lower row of simulated shingles. A ledge, generally coplanar with the bottom wall of the upper row of shingles, extends rearwardly of the bottom end portion.
A lead fin extends laterally outwardly of the upper row of simulated shingles. The lead fin has a lateral end spaced laterally outwardly of the upper row. A groove below the lead fin extends between the lateral end and the upper row. Plastic panels of the invention fit together with a middle ledge of a first panel engaging a lead fin of a second panel adjacent the first panel.
A particularly preferred plastic panel includes at least one laterally extending row of simulated shingles having a simulated wood appearance. A panel with two rows of simulated shingles is most preferred. The simulated shingles each include a bottom wall extending between longitudinally extending shingle side walls. The side walls preferably are generally parallel to each other and to adjacent side walls on other shingles in each row.
Opposed side walls on adjacent simulated shingles define a plurality of gaps each having a predetermined width, defined herein as the average distance between opposite side walls. These gaps each have a width that varies randomly within predetermined limits in order to camouflage the lateral spacings between adjacent panels that vary because of thermal contraction and expansion. For example, systems mounted with xc2xc inch average lateral spacings between shingles in adjacent panels will have gaps between adjacent simulated shingles averaging about a xc2xc inch width. However, the gap width varies randomly between about xe2x85x9 inch and ⅝ inch, thereby camouflaging spacings that vary because of thermal contraction and expansion.
In an alternative embodiment of the invention, the plastic panel is injection molded to include a body having side walls on opposite lateral sides, a top wall extending between the side walls, and an elongated strip extending outwardly of the top wall. The strip includes a locking tab spaced from the top wall and a laterally extending folding hinge between the locking tab and the top wall. The folding hinge extends between the side walls and has reduced thickness compared with the remainder of the strip.
The strip is folded along the folding hinge so that adjacent opposed surfaces on the strip define a fastening line. The opposed surfaces are then joined together by heat or ultrasound or mechanically to form an integral structure.
An important advantage of this embodiment is that the locking tab can be made continuous, extending without interruption between the side walls and without any openings behind the locking tabs.